Established on December 2, 1980, the park is located on the Alaska Peninsula, across from Kodiak Island, with headquarters in nearby King Salmon, about 290 air miles southwest of Anchorage. Originally, on September 24, 1918, the area was designated a national monument to protect the area around the major 1912 volcanic eruption of Novarupta, which formed the Valley of Ten Thousand Smokes, a forty square mile (100 km²), 100 to 700 foot deep, pyroclastic flow.
Activities at Katmai include hiking, backpacking, camping, backcountry skiing, fishing, kayaking, boat tours, and interpretive programs. There are at least fourteen active volcanoes within the national park, most recently Fourpeaked Volcano, which became active September 17, 2006 after more than 10,000 years of dormancy. This park contains numerous archaeological sites which indicate a long history of prehistoric occupations from the Paleoarctic tradition up to the Thule tradition.
Katmai is also well known for brown bears and the salmon which attract both bears and people. Katmai contains the world's largest protected brown bear population, estimated to number in excess of 2,000. Bears are especially likely to congregate at the Brooks Falls viewing platform when the salmon are spawning, and many well known photographs of brown bears have been taken there. The coastal areas such as Hallo Bay, Kukak Bay and Chiniak host the highest population densities year-round, due to the availability of clams and edible coastal sedge as well as salmon and other fish.
The vast majority of Katmai visitors come to Brooks Camp, one of the only developed areas of the park, and few venture further than the bear viewing platforms. Rangers at the park are extremely careful not to allow bears to obtain human food or get into confrontations with humans. As a result, bears in Katmai Park are uniquely unafraid of and uninterested in humans, and will allow people to approach (and photograph) much more closely than bears elsewhere.